U.S. Pat. Nos. 4,281,645, 4,223,680, and 5,119,815 describe non-invasive measurement of biochemical components, such as hemoglobin (H), oxyhemoglobin (HbO.sub.2), and cytochrome (CyOx) in a human or animal body. These systems introduce a beam of electromagnetic radiation in the form of infra-red light into the body at one point, sense the radiation emerging at another point, process the sensed data in a processor, and display or graph the results. U.S. Pat. No. 4,281,645 involves transillumination across the body from one point to an opposing point on the other side of the body. U.S. Pat. No. 4,223,680 discloses measuring along spaced parts of the body and using two detectors, one located near the light source to correct for light scattered from the skin. U.S. Pat. No. 5,119,815 entails using a pulsed light source.
These methods attempt to determine characteristics of such components on the basis of certain assumptions of the correlation between light intensities and the average light paths. However, it is believed that these assumptions lead to inaccuracies that arise from changes in the average light paths with changes in the concentration of the components.
An object of the invention is to improve prior art systems.
Another object is to overcome the aforementioned problems.
Still another object is to provide improved measurement optrode.
Yet another object is to provide a measurement system which permits accurate measurement of concentration of biochemical compounds.